Immunophenotype and function of T cells overexpressiong CCR4 are retained. (A) The phenotypic composition of NT () and CCR4⁺ (■) T cells. The data are mean ± SD of 5 healthy donors. T-cell markers are shown on the x-axis. No significant differences were observed if cells overexpressed CCR4. (B) Expression of naive, central memory, and effector memory surface markers on CTR () and CCR4⁺ (■) T cells is not significantly different. The data are mean ± SD of 4 donors. (C) The production of Th1 (IFN-γ and TNF-α) and Th2 (IL-10 and IL-4) cytokines by CTR () and CCR4⁺ (■) T cells 24 hours after stimulation with OKT3. No significant differences in cytokine production were detected, suggesting that the transgenic expression of CCR4 does not induce the acquisition of a Th2 profile. (D) CCR4⁺ T cells do not acquire inhibitory function. The inhibitory activity of T cells was evaluated using a CFSE-based suppression assay in which PBMCs labeled with CFSE are stimulated with irradiated allogeneic PBMCs and OKT3 in the absence (top left graph) or in the presence of freshly isolated CD4⁺CD25^bright cells (top right graph), CTR (bottom left graph), or CCR4⁺ T cells (bottom right graph). The panel indicates a significant number of divisions (CFSE partitioning) of T cells in the absence or presence of CTR or CCR4⁺ T cells (evident in the left quadrants). In contrast, the divisions are significantly reduced in the presence of Treg cells. Shown is one of 3 donors studied, illustrative of results from all.